1   $ hg init

     2   $ touch a

     3   $ hg add a

     4   $ hg ci -m "a" -d "1000000 0"

     5 

     6   $ echo 123 > b

     7   $ hg add b

     8   $ hg diff --nodates

     9   diff -r acd8075edac9 b

    10   --- /dev/null

    11   +++ b/b

    12   @@ -0,0 +1,1 @@

    13   +123

    14 

    15   $ hg diff --nodates -r tip

    16   diff -r acd8075edac9 b

    17   --- /dev/null

    18   +++ b/b

    19   @@ -0,0 +1,1 @@

    20   +123

    21 

    22   $ echo foo > a

    23   $ hg diff --nodates

    24   diff -r acd8075edac9 a

    25   --- a/a

    26   +++ b/a

    27   @@ -0,0 +1,1 @@

    28   +foo

    29   diff -r acd8075edac9 b

    30   --- /dev/null

    31   +++ b/b

    32   @@ -0,0 +1,1 @@

    33   +123

    34 

    35   $ hg diff -r ""

    36   abort: 00changelog.i@: ambiguous identifier!

    37   $ hg diff -r tip -r ""

    38   abort: 00changelog.i@: ambiguous identifier!

    39 

    40   $ true